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Which bacteria is known for causing a disease characterized by a pseudomembrane in the throat?
- A. Clostridium tetani
- B. Bordetella pertussis
- C. Corynebacterium diphtheriae
- D. Streptococcus pyogenes
Correct Answer: C
Rationale: The correct answer is C: Corynebacterium diphtheriae. This bacterium causes diphtheria, a disease characterized by a pseudomembrane in the throat. This pseudomembrane is a result of the bacterial exotoxins causing inflammation and necrosis of the throat tissues. Clostridium tetani (A) causes tetanus, characterized by muscle stiffness, not a pseudomembrane in the throat. Bordetella pertussis (B) causes whooping cough, with symptoms of severe coughing fits but no pseudomembrane. Streptococcus pyogenes (D) causes strep throat, but does not produce a pseudomembrane.
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The so-called “red tide†is generally caused by which of the following organisms?
- A. Lichens
- B. Bacteria
- C. Pfiesteria
- D. Dinoflagellates
Correct Answer: D
Rationale: The correct answer is D: Dinoflagellates. Red tides are caused by the rapid growth of certain species of dinoflagellates, which are single-celled algae. These algae produce toxins that can harm marine life and humans. Lichens (A) are not associated with red tides. While some bacteria (B) can contribute to harmful algal blooms, they are not the primary cause of red tides. Pfiesteria (C) is a type of harmful algal species, but it is not the main organism responsible for red tides. Therefore, the correct answer is dinoflagellates (D) due to their ability to cause red tides through toxin production.
Which form of human plague is present with high fever and large lymphadenopathies (buboes). The case fatality in untreated cases may reach 60%.
- A. Bubonic plague
- B. Pneumonic plague
- C. Gastrointestinal plague
- D. Septicemic plague
Correct Answer: A
Rationale: The correct answer is A: Bubonic plague. Bubonic plague is characterized by high fever and large swollen lymph nodes (buboes). The case fatality rate in untreated cases can reach 60%. This form of plague is typically transmitted through the bite of an infected flea.
B: Pneumonic plague presents with respiratory symptoms and is transmitted through respiratory droplets.
C: Gastrointestinal plague is not a recognized form of plague.
D: Septicemic plague is a severe form of plague where the bacteria multiply in the bloodstream. It may not always present with buboes.
A patient complained about a carbuncle on his face. Examination results: neither dense nor painful edema of subcutaneous cellular tissue, there is black crust in the middle of the carbuncle and peripheral vesicular rash around it. Bacteriological examination revealed presence of immobile streptobacilli able of capsulation. What microorganisms are causative agents of this disease?
- A. Bacillus antracis
- B. Staptylococcus aureus
- C. Bacillus anthracoides
- D. Bacillus megaterium
Correct Answer: C
Rationale: The correct answer is C: Bacillus anthracoides.
1. The patient's symptoms align with cutaneous anthrax, caused by Bacillus anthracis.
2. Presence of immobile streptobacilli able of capsulation matches the characteristics of Bacillus anthracis.
3. Symptoms such as black crust, peripheral vesicular rash, and non-painful edema are classic for cutaneous anthrax.
4. Choice A: Bacillus antracis is a misspelling, not a valid option.
5. Choice B: Staphylococcus aureus does not match the symptoms described in the scenario.
6. Choice D: Bacillus megaterium is not associated with cutaneous anthrax.
Urine examination of a patient with acute cystitis revealed leukocytes and a lot of gram-negative bacilli. Inoculation resulted in growth of colonies of mucous nature that formed green soluble pigment. What microorganism is the most probable cause of the disease?
- A. Pseudomonas aeruginosa
- B. Klebsiella pneumoniae
- C. Escherihia coli
- D. Salmonella enteritidis
Correct Answer: C
Rationale: Rationale:
1. Presence of gram-negative bacilli suggests Enterobacteriaceae family, which includes E. coli.
2. Green soluble pigment indicates pyocyanin production, characteristic of E. coli.
3. E. coli is the most common cause of acute cystitis due to its ability to colonize the urinary tract.
Summary:
A: Pseudomonas aeruginosa is not typically associated with acute cystitis and does not produce mucous colonies.
B: Klebsiella pneumoniae may cause UTIs, but does not produce green pigment and is less common than E. coli.
D: Salmonella enteritidis is associated with gastrointestinal infections, not cystitis.
Streptococci are:
- A. Gram-positive, short rod shaped bacteria and size 4-6 µm
- B. Gram-negative, rounded or lanceolate shape and size 0,5-1 µm
- C. Gram-negative, short rod shaped bacteria and size 4-6 µm
- D. Gram-positive, spherical or lanceolate shape and size 0,5-1 µm
Correct Answer: D
Rationale: The correct answer is D because Streptococci are Gram-positive bacteria, typically spherical in shape, and range from 0.5-1 µm in size.
A is incorrect as streptococci are not rod-shaped and are usually smaller in size. B is incorrect as they are not Gram-negative and are not typically of such small size.
C is incorrect as streptococci are not Gram-negative and are not usually rod-shaped. Thus, based on their characteristics, the correct answer is D.